[Info-vax] Loosing all LAT connections on one machine in DECNet Network

[Bill Gunshannon]

In article <BBHFl.5603$Lr6.5562 at flpi143.ffdc.sbc.com>,
	Chris Scheers <chris at applied-synergy.com> writes:
> JF Mezei wrote:
>> Chris Scheers wrote:
>> 
>>> The DELNI was connected to the company network, which was primarily 
>>> 100MB.  Periodically, something on the 100MB network would start 
>>> generating enough data to swamp the 10MB DELNI, causing LAT to go down.
>> 
>> In this case the "DEC" ethernet segment would be fully paralysed, and
>> LAT announcements from the PDP-11s would also go away. This chap's
>> problem is that only the VAX's LAT service disapears from the decserver.
>> 
>> 
>>> Putting a 10MB switch between the rest of the network and the DELNI 
>>> solved the problem.
>> 
>> If the main ethernet segment has a broadcast storm, then the switch
>> would relay all broadcast packets over to the DEC ethernet segment and
>> swamp it.
> 
> Networks can be funny.  In this case, there was enough traffic to make 
> LAT unreliable but not enough to completely swamp the DELNI.  DECnet and 
> Pathworks stayed up.
> 
> Also in this case, it wasn't a broadcast storm.  It was application 
> chatter between two nodes.  (Yes, some of their traffic wasn't switched.)
> 
> If you have a broadcast storm you will probably need a bridge to isolate 
> the traffic.  (As well as good knowledge about which broadcasts need to 
> get where.)
> 

While I still have a DELNI or two, they are mostly for curiosity.  You
should seriously consider getting 10BaseT transcievers and hooking these
boxes up to a switch to cut extraneous traffic.  I seem to remember PDP-11's
having a real problem when VAXes started showing up on networks.  Seemed
like swamping the ethernet (which a VAX could easily do) would not just
drop connections but actually bring a PDP-11 down,

bill

-- 
Bill Gunshannon          |  de-moc-ra-cy (di mok' ra see) n.  Three wolves
billg999 at cs.scranton.edu |  and a sheep voting on what's for dinner.
University of Scranton   |
Scranton, Pennsylvania   |         #include <std.disclaimer.h>